All the Ghostbusters--the originals, the ladies of the 2016 film, and beyond--come together against a threat too powerful for any one team to handle alone. For a while now, the original Ghostbusters have had access to an interdimensional portal that has given them all-new ways to research the paranormal and consult with Ghostbusters throughout the multiverse... but they haven't shared this tech with any of those other Ghostbusters, and some don't...